Method of processing black liquor and product derived therefrom



Patented Oct. 28, 1930 UNITED STATES PATENT OFFICE EDWARD G. GOODE LL,OF STEVENS POINT, WISCONSIN No Drawing.

This invention relates to a method of processing black liquor and to aproduct derived therefrom. i

In my copending applications, Process of treating black liquors, SerialNo. 329,385,

filed December 31, 1928; Method of dehydrating black liquors, Serial N0. 351,660,

filed April 1, 1929, and Process of regenerating black liquors SerialNo. 351,661, filed April 1, 1929, certain processes are described whichrelate to the recovery and regeneration of the-chemical values and theutilization of the heat values contained in the so-called black liquorsresulting from the manufacture of pulp by the soda or sulphate processor combinations or modifications thereof.

. The above applications in particular disclose a process of dehydratingblack liquors by spraying the black liquor into a heated gaseous dryingmedium, such as waste flue gases, wherein removal of the moisturecontent of the black'liquor is effected without decomposition ordestruction of its solid organic and inorganic constituents. The productresulting from my spray drying process, which is claimed herein as apart of my present invention, is a finely divided solid substance orblack liquor residuum, containing all of the organic and inorganicvalues originally present in the black liquor solution. These valuesconsist principally of the heat content of the organic matter which isseparated from the wood or other cellulosic raw material in the processof cook,- ing, and the sodium and sulphur content of the inorganiccompounds such as sodium hydroxide, sodium carbonate, sodium sulphate,sodium sulphide, and the like, contained in the cooking liquors.

The steps in my process of reclaiming these values include thegeneration of steam in standard steam boiler equipment and the smeltingor fusion of the sodium compounds in a smelting furnace wherein, in thecase of the sulphate roce ss, a high percentage of the sodium su hurcompounds contained in the dried blac liquor powder and added thereto asmake-up salt cake (sodium, sulphate, Na SO is reduced to the activecooking agent, sodium sulphide.

Application filed October 26, 1929. Serial No. 402,802.

As described in my copending applications above listed, the dried blackliquor powder is delivered to the smelting furnace (usually with anintimate admixture of make-up salt cake) in the same finely dividedcondition as produced in the spray dryer.

In the commercial scale development of this process, however, I havediscovered that a further treatment of the dried black liquor substancemay be advantageously employed so to improve its physical condition.

g It is therefore .an object of this invention to provide a. roductcomprising the solid constituents 0 black liquor containing all of theorganic and inorganic values originally present in the black liquoritself.

It is a further important object of this inventlon to provide a productcomprising the solid constituents of black liquor in compressed solidunits, or lumps, capable of holdingtheir shape reasonably intact whenhandled and especially adapted for use in the processing of black liquorto recover the heat values thereof and to recover and, regenerate thechemical values contained therein.

It is a further important object of this invention to provide a processof regenerating black liquor in an improved and more efficient manner. 7

Other and further important objects of this invention will becomeapparent from the following description and appended claims.

While dried black liquor powder such as may be obtained by the sprayprocess described in my aforementioned copending 5 applications, (eithermixed with salt cake or not) may be introduced into the smelting furnaceeither in a continuous flow or periodically in comparatively largeamounts, there frequently results a more or less encrusting or buildingup into a solid mass in the smelter of large bodies of the dried powder,making necessary more or less manual labor and attention in order tobreak up this solid or encrusted mass in order to maintain propercirculation' of air or gases inside the smelting furnace and otherwisepromote furnacing operations. Moreover, when feeding a dry fine- 1ydivided black liquor powder into the smelting furnace, there is atendency on the part 1 of some of the powder to floatorfremain Sus iended in the air orgases inside the smelting urnaceand to burn while insuch suspended condition, resulting in a loss of .sodas in the' fluegases in the shape of finel divided parti cles as dust or in the form 0volatilizedfso dium compounds.

In order to improve these conditions in the smelting furnace .I preferto compress or mold the black liquor solids or residuum into 1 separatesolid lump-like shapes and feedsuch lumps or the like into the smeltingfurnace limiting the patent granted hereon otherwise than necessitatedby the'prior art. i

,I claim asmy invention:

1. As a new article of manufacture, a solid product consisting of the\compressed solid constituentsof black liquor substantially unchanged asto chemical composition.

2. As a new article of manufacture, comtpressed black liquor solids inthg form of,

ense' units ada ted for handling, storing, transporting an the like. I

3. n the process of treating black liquor,

in order that a more open or porous bed may the step which comprisescompressing the be secured, together with improvedredu'cing and smeltingconditionsand increased furnace capacity. v p

This method may be employed as a continuous step in compressing ormolding black liquor substance just prior to its delivery to thesmelting furnace, or it may be employed as a means of converting black'liquor subing black liquors. It is not necessary that the black liquorsubstance be completely dried,

stance into a more convenient form for stor age, transportation,handling or sale. For example, the smelting furnaces and smeltingoperations may in certain casesbe more advantageously operated at alocation apart from the drying operations. v

The advanta es of this improvement are not limited to 5m spray dryinprocess, but are also applicable vto other met ods of treatnor that itbe produced by any particular preliminary method of evaporation, s ray-1ng, dryin or concentration, provide the solid constltuents of the blackhquor are obtained substantiall unchanged as to chemical composition. tmay be practiced in connection with my spray drying process as aforesaidor it may be racticed 1n connection with any other method by which blackliquor substantially dry solid constituents of black liquor intoseparate units capable of holding their shapes reasonably intact inhandling.

4. In the process of treating black liquor, the step which comprisessubjecting thesolids of black liquor to a smelting operation while inthe form of compressed units.

In testimony whereof I have hereunto subscribed my, name at StevensPoint, Portage County, Wisconsin.

EDWARD G. GOV'ODELL.

substance is brought to such physical condition that it may becompressed or molded into lumps or sha es possessing suflicientadherhandling.

. In this connection it may be once to holdt eir shape reasonably intactin I stated that black liquor substance either wholly dried or partiallydried or mixed to a plastic consist- 'ency is particularly well adapted.to this pressing or molding process, being of a vis-" cous adhesivenature, particularly when .heated, and may be compressed to an extremelyhard dense structure similar to that of bituminous coal. As anindication of the twenty-five pounds or more as may be suitedto-individual convenience in handling and/or desired results infurnacing.

I am aware that numerous details of the I process may be varied througha wide range without departing from the principles of this a

